Woven hook and loop closure parts, whose warp, weft, and functional threads may be formed of textile fibers. Plastic or metal fibers are also readily available on the market in a host of embodiments. The functional threads in the backing fabric of warp and weft threads form loop-shaped interlocking elements, provided they are formed from multifilament threads. If the functional threads are formed from monofilament fibers, these closed loops are cut apart or thermally separated from one another to form closure hooks which can be caused to engage the correspondingly made fleece loop material of the other closure part of the fastening system. Closures such as these are characterized by recurring potential opening and closing processes.
Fastening systems such as these are increasingly being used in transportation and aircraft engineering, for example, for attachment of wall panels to the carrier structure of a railway car or for attaching seat covering materials to aircraft passenger seats or the like. Especially in the area of aeronautic engineering increased demands are imposed at present on these fastening systems for low flammability. These demands are much stricter than earlier specifications, for example, in the form of EADS Specification FAR25.853(b).
To satisfy that regulation, for example, EP-A-1 275 381 proposes coating a hook and loop closure part having closure elements with a flame retardant medium on the surface side and/or incorporating the pertinent flame-retardant medium into the closure itself. As the coating method, for example, an immersion process is suggested, with the flame-retardant media substances and substance groups being such as phosphorus, graphite, nitrogen and antimony compounds and aluminum derivatives and hydrates. Furthermore, the use of organic phosphorus substances is described. For better joining of the flame-retardant medium to the closure material, the use of a binder, for example, in the form of vinyl acetate, is proposed. Although the known closure on its top can be completely surrounded by the flame-retardant medium, or at least is formed partially of the flame-retardant medium itself, these measures are not currently adequate to meet the more stringent flame protection guidelines.
EP-B-0 883 354 discloses a flame-retardant fastening element which, as part of a fastening system for detachable engagement, is matched to a second fastening element having a substrate layer of a flame-retardant polymer material into which U-shaped clamps are placed. The legs of the clamps form stem sections which on their free end and projecting from the substrate layer each form a closure head. The closure elements formed in this way as closure mushrooms are securely anchored in the substrate layer on the base side by the clamp crosspiece. For attaching the fastening element to outside parts such as vehicle components or the like, a non-flame-retardant, pressure-sensitive cement is used and applied to a support surface facing away from the top of the substrate layer with the projecting fastening heads as part of the fastening element. In the known solution, for one preferred embodiment the non-flame-retardant, pressure-sensitive cement is a foam layer of a pressure-sensitive acrylic foam cement. Cements with this structure are detailed, for example, in WO-A-2005/017060. This solution forms a flame-retardant closure with very good action, but can be expensive in implementation, especially with respect to placing the U-shaped fastening elements in the substrate layer.
In addition to using conventional plastic materials as cited above in the form of polyethylene, polyamide or the like for the closure material, EP-B-0 198 182 discloses the use of carbon fiber materials for implementation of a flame-retardant closure. In this known solution, with the formation of a flame-retardant closure both the loops and the backing material of the loop part as the backing fabric from which the loops project are formed of carbon fibers. The hooks of the hook part itself should be formed from wire. Although in the known solution both the loop part and also the hook part have a textile character so that they can be processed like conventional textile hook and loop closures, in particular sewn on, their flame resistance far exceeds that of textile hook and loop closures of the conventional type, specifically 1,000° C. The use of carbon fiber materials has, however, proven very costly, since carbon material is only available to a limited degree, at least for the present.